Septum posticum cysts: an uncommon cause of chronic back pain.

The authors describe two patients with posterior thoracic pain associated with cysts of the septum posticum. One patient's pain was relieved by surgical removal of the cysts; the second patient's symptoms temporarily resolved after myelography. Posterior thoracic pain can be ascribed to myelographically proven arachnoid cysts when the pain is persistent, positionally exacerbated and associated with radicular sensory changes. Excision of the cysts may provide pain relief for some patients.